Stunt Double MCP Server

Deploy AI user personas to validate user journeys at scale. Find UX friction before real users do.

Stunt Double deploys AI agents with realistic user personas to validate user journeys at scale. Create actors, run automated workflows and checklists against any web app, and surface friction points before real users encounter them. Integrates with Claude, Linear, GitHub, and Slack.

This repository

This repo holds plugin and MCP configuration (.claude-plugin/plugin.json and .mcp.json for Claude, .cursor-plugin/plugin.json and root mcp.json for Cursor, server.json for the MCP registry), plus skills, agents, and Cursor rules. There is no package.json and no runnable server here: the MCP endpoint is hosted at https://app.stuntdouble.io/api/mcp from the main Stunt Double codebase. See CONTRIBUTING.md for how to validate edits and avoid confusing this folder with a Node package.

Related MCP server: UserFlow MCP

Quick Start

Claude Code

claude mcp add --transport http stuntdouble https://app.stuntdouble.io/api/mcp

Claude Code plugin

The repository is also a Claude plugin: it bundles the hosted MCP server (.mcp.json) with the skills in skills/ and the agents in agents/.

claude plugin marketplace add stunt-double/stuntdouble-mcp
claude plugin install stuntdouble@stuntdouble

Skills (any agent)

The skills in skills/ install into Claude Code, Cursor, Codex, OpenCode and other agents that read SKILL.md files, using the skills CLI. They drive the MCP server above, so connect that too.

npx skills add stunt-double/stuntdouble-mcp                          # pick from the list
npx skills add stunt-double/stuntdouble-mcp --skill verify-change     # just one

Claude (web, Desktop, mobile)

Go to Settings → Connectors → Add custom connector and paste:

https://app.stuntdouble.io/api/mcp

Cursor / Windsurf

Add the mcpServers block below to an MCP config file:

• Project-local (recommended for this repo clone): .cursor/mcp.json at the root of your project.

• Global (all projects): ~/.cursor/mcp.json on macOS/Linux (see Cursor MCP docs for your OS).

{
  "mcpServers": {
    "stuntdouble": {
      "url": "https://app.stuntdouble.io/api/mcp"
    }
  }
}

Use only url for remote servers (Streamable HTTP is negotiated automatically). Extra keys such as "type": "streamable-http" are not part of Cursor's documented mcp.json shape and can break plugin validation.

Cursor marketplace (one-click install) expects a plugin layout: .cursor-plugin/plugin.json plus root mcp.json. Those files are in this repo. The plugin logo path is assets/logo.png (bundled in this repository). The server.json file is the separate MCP registry manifest for mcp-publisher and directory listings; Cursor's installer does not use it.

Authentication

Authentication is handled automatically via OAuth 2.1 with PKCE. The first time your AI client connects, a browser window will open for you to sign in and authorise access to your Stunt Double account. No API keys or tokens required.

For Cursor, the OAuth redirect URI is fixed to cursor://anysphere.cursor-mcp/oauth/callback (docs).

What a connection can reach

The server acts as you, never more. Every tool resolves the workspace it is being asked about and checks your membership of it before doing anything, so a connection reaches exactly the workspaces list_workspaces returns for you, and an archived workspace reaches nothing. A workspace you are not a member of answers the same way one that does not exist does: "not found".

That holds for ids too, not just the workspace_id you pass. A tool that takes another object's id (a checklist for an automation step, an actor for an interview participant) checks that object belongs to the same workspace before storing or running it, and refuses with "not found in this workspace" otherwise. Refusals never say which workspace an id does belong to.

Scopes narrow this further, never widen it. The consent screen names what the connection asked for, and a token granted mcp:read is not shown the write or run tools at all: they are absent from tools/list rather than present and failing.

Available Tools

Account

Notification channel and timezone are account settings rather than workspace ones, so they are the same answer in every workspace. Pass the timezone when creating a scheduled workflow, or "every weekday at 9" becomes nine in UTC.

Workspaces

get_workspace reports the workspace security controls under settings: public sharing, the feedback widget, self-hosted workers, and the network policy. They are ceilings set by an admin, so a feature switched off there cannot be switched back on for a single project.

Search

search takes a workspace_id plus an optional query, types filter, project_id filter and limit (max 50). Terms are matched as prefixes, so a partial word is enough. Omit query to browse the most recently updated items. Results carry the id you need for the matching getter, so it is usually cheaper than listing an entity type and filtering the list yourself. Reach for it before creating anything, to find the actor or checklist that already covers the job.

Projects

A project is archived, never deleted, and an archived project reads as missing from every tool here. Registering an MCP server and attaching it to a project are workspace-admin actions in the dashboard; list_project_mcp_servers is how you check what tools a run will actually have before writing a checklist that depends on one.

Guidelines

Standing rules the team holds the product to: design system, tone of voice, brand, content, accessibility, compliance, security, performance, or shared knowledge. A guideline is owned by the workspace and attached to the projects it applies to, so one rule can hold for every project without being retyped. Whatever is in force is rendered into every checklist run, design review, interview and triage for that project.

Two switches decide whether a rule is in force for a project: the library's enabled and the attachment's. list_project_guidelines folds them into one enabled so you never have to reason about both. A rule with apply_to_design_reviews set also holds for design reviews raised from Slack or Linear, which carry no project to attach it through.

Codify a standard as a guideline rather than repeating it in each checklist, and search the library before writing a new rule: attaching the one that already exists keeps the team's standard in a single place to edit.

Actors

Knowledge

Conversations

Checklists

Workflows

A workflow is a graph, not a list: its steps run by following the connections between them. The step tools maintain those connections, so adding, removing and reordering steps is enough to build one. connect_workflow_steps is only needed to branch.

Feedback

GitHub

Interviews

Structured user interviews: actors or generated personas run through a discussion guide (sections + questions/tasks) against a target URL, then Stunt Double synthesises themes and recommendations.

Prompts

Most MCP clients (Claude, Claude Code, Cursor) surface these as slash commands. Each is a self-contained recipe: which tools to call, in what order, and how to report back.

Resources

Read-only context a client can attach without calling a tool. The guide and the connection are always listed; the workspace resources need mcp:read, the same as the tools that return that data.

resources/list includes one projects entry per workspace, so a client can browse them without expanding the template.

Stunt Double Index

The Stunt Double Index is a public ranking of how AI agents experience websites: each tracked domain is scored out of 100 from HTTP probes plus live agent sessions, one per AI provider and benchmark task. Index data is public rather than workspace data, so the read tools reach any tracked site.

get_index_report, list_index_sessions and request_index_rerun take a domain, or a project_id to use the Index domain linked to that project (which checks your membership like any project read). Only the domain's owner can re-run it: a platform admin, the person who claimed it, or, while it is unclaimed, someone signed in with a work email on that exact domain. After a re-run, poll list_index_sessions with the returned run_id until the sessions finish, then read get_index_report. (inviting/removing members) is available in the web dashboard.

Example prompts

Four prompts that exercise the core of the server once it is connected:

1. Verify a flow: "Create a checklist that signs up for a new account on https://demo-checkout-stunt-double.vercel.app, adds an item to the basket and reaches payment, then run it and tell me which checks failed."

2. Run a user interview: "Set up an interview with three personas (a first-time shopper, a returning customer and a screen reader user) about our pricing page, launch it, and summarise the report."

3. Check agent readiness: "How well can AI agents use stripe.com according to the Stunt Double Index, and which categories are dragging its score down?"

4. Triage feedback: "Summarise the open feedback on my main project, group it into themes, and mark anything already fixed as resolved."

Privacy Policy

The server is hosted by Stunt Double and acts as the signed-in user. It reads and writes only the workspaces that user belongs to, within the OAuth scopes they grant (mcp:read, mcp:write, mcp:run). It does not read your conversation with the AI client beyond the arguments passed to each tool call, and it does not access the client's memory, chat history or files.

Data created through the server (projects, actors, checklists, runs, interviews, feedback) is stored in your Stunt Double workspace and handled under the Stunt Double Privacy Policy, which covers collection, use, storage, sub-processors, retention and your rights. Revoke a connection at any time by disconnecting it in your AI client.

Support

• Email: support@stuntdouble.io

• Help centre and docs: stuntdouble.io/support

• MCP reference: stuntdouble.io/support/docs/api/mcp

• Security reports: see SECURITY.md

Transport

This server uses Streamable HTTP transport. The endpoint is:

https://app.stuntdouble.io/api/mcp

MCP Registry

The server is listed in the official MCP Registry as io.stuntdouble/mcp-server, so registry-backed clients and directories can find it by name:

curl "https://registry.modelcontextprotocol.io/v0.1/servers?search=io.stuntdouble/mcp-server"

Each version merged to main is published there automatically (see CONTRIBUTING.md).

Links

• Website

• Documentation

• MCP server reference

• Privacy Policy

• Terms of Service

• llms.txt

Verifying changes

From the repo root:

node scripts/validate-json.mjs
npx --yes prettier@3.4.2 --check README.md CONTRIBUTING.md SECURITY.md CHANGELOG.md mcp.json .mcp.json server.json .cursor-plugin/plugin.json .claude-plugin/plugin.json .claude-plugin/marketplace.json

More context in CONTRIBUTING.md. GitHub Actions runs the same checks on push and pull requests.

License

MIT